A major source of preoccupation in modern society has been the amount of waste produced and its impact in the environment, increasing pollution and using valuable spaces as landfill. Thus, there has been great interest in the manufacture of biodegradable disposable articles, and especially when these are made from recycled or discarded material.
One application for biodegradable disposable containers is in the agricultural sector, for example in plant nurseries and green houses. Plants are grown in pots until they are mature enough to be distributed to retail outlets or to consumers. Typically, molded non-biodegradable plastic pots are used for growing plants, which end up being discarded after the plant is transplanted into the soil. The pots then end up in landfills or garbage dumps, where they remain for a very long time since they are not biodegradable.
Alternatives to conventional plastic pots exist. Biodegradable pots made of paper (cellulose fibers), peat and other organic waste are known. These pots are designed to degrade relatively quickly when buried in soil. This allows consumers to simply bury the pot with the plant in it, rather than having to remove the plant from the pot before planting. However, the biodegradable pots must also be substantially resistant to saturation by liquids so that they do not begin to disintegrate prior to being buried in soil.
Some biodegradable pots include a thermoplastic polymer layer which faces an interior of the plant pot which is exposed to soil placed in the plant pot. However, methods of irrigation and the humid environment in many nurseries cause the external surfaces of pots to be exposed to moisture, so that a sealant on the interior of a plant pot does not prevent degradation of the pot while still on the shelf in the nursery.
Nurseries also use plug trays for plant transplants. In plug trays each transplant grows in an individual cell avoiding competition among plants and providing uniformity of the plants.
Planting seedlings in the field typically involves extracting each plug out of the tray and transplanting it in soil. Transplanting often causes shock due to damaged done to the roots while being extracted from the tray.
The standards by which the quality of planting is measured include placing the seedling plugs without exerting damaging pressure on the roots, evenly spacing the seedlings, planting the seedlings upright and properly covering the plugs. By these standards automated transplanting produces better results than manual transplanting. Thus, transplantation nowadays is mostly automated (particularly in rich countries). However, automated transplanting requires the use of large expensive transplanter machines, or cheaper machines that require the use of human labor. Furthermore, the transplanter machines only works efficiently in dry and broken up soils. Unfortunately, transplanting in dry soil in hot climates can be fatal for the young plants. Thus farmers typically irrigate the soil before transplantation, which results in muddy fields which hinder the functioning of the transplanter machines.